From my perspective, the fix you propose is a regression in functionality. In earlier versions of Unity, the font system did not require you to import TTF/OTF font data into your game app (Unity Player) in order to generate static font atlases. The Font Atlas Generator tool should be able to generate fonts without having to include TTF/OTF font data in the game. If the generator needs this data in order to do it’s work, then it should temporarily load the data and then restore the “not included” setting after the atlas has been generated. The burden of this work should not be on the user. My game app, for example, has nearly a dozen fonts with static atlases, so regenerating these by having to set and clear this setting for each font every time would be very time consuming. Again, this was not required in earlier versions of Unity (e.g. 2021.3).

If you check "Include Font Data" then it works. However, in earlier versions of Unity/TMPro, you did not have to include font data to generate font atlases. This is the proper behaviour because OTF/TTF font data is not required for FontAssets that use only pre-generated atlases.